The contemporary communications network is generally built with devices from multiple networking layers, such as a routing layer over an optical layer that includes Reconfigurable Optical Add/Drop Multiplexers (ROADM). These devices may come from one or more vendors. Each vendor or each layer may have its own discovery mechanisms or management tools. An example of cross-layer interface mapping includes discovering which router port (layer 3) is connected to which ROADM Add port (layer 0). Generally, cross-layer connections can be a grey router interface connecting to a transponder or a colored router interface connecting to a multiplexer or demultiplexer port of a ROADM. For grey interfaces, cross-layer mapping may be derived from interface statistics or protocol snooping on the transponder.